Children,
Cancer, and the Environment

What cancers affect
children?

The types of cancer that
children experience are very different from those of adults. None of the most
common adult cancers - prostate (in men), breast (in women), lung, or colon
- are found in children.

Instead, leukemia
is the most common cancer in all children, representing 31.5% of cases in children
under 15. Next most common are central nervous system cancers including
brain cancer (20.2%), lymphomas including Hodgkin’s disease and non-Hodgkin’s
lymphoma (10.7%), neuroblastoma and other cancers of the nerves (7.8%),
soft tissue sarcomas (7%), kidney cancers (6.3%), and cancer of the bones (4.5%)
(1).

The patterns of cancer
vary a lot at different ages. The cancers most common in very young children
are different from those in children of pre-school age and different again from
those most common in adolescents.

For infants, neuroblastoma
is the most common form of cancer, accounting for 28% of cases. Leukemia (17%),
central nervous system tumors (13%), retinoblastoma (12%) and Wilms tumor (9%)
were the next most common (2). Male and female infants
have equivalent rates of cancer. Overall, 233 cases were diagnosed per million
infants. White infants have 40% more cancer than black infants.

The types of cancer found
most often in children up to 15 years old are leukemia, brain and central
nervous system cancers, lymphoma, soft tissue sarcomas, kidney tumors, and cancer
of the bones.

The most common cancers
inadults affect different types of tissues than the cancers
in children. In adults, the tissues most affected by cancer are those that
cover parts of the body (including internal parts or organs.) These are called
"epithelial" tissues and include tissues in the colon, lung, and breast.
The accumulation of damage to cells over the years can cause cancer in such
tissues. Damage to the lungs from smoking would be a good example. Because
children are young, such long-term, accumulated damage has not had a chance
to occur. The causes of cancer in children are likely to be different from
causes of many cancers in adults. Most cancer in children forms in connective
tissues, the blood, or the nervous system, not in epithelial cells.

In California, leukemia
is the leading cause of cancer mortality in persons up to age 19. Leukemia causes
more than 35% of deaths for people in this age group, while brain and nervous
system cancers cause about 22% of deaths, and lymphomas cause about 8% (3).